The present invention relates to an electrode for an electrochemical cell, having a solid electrolyte interface layer. More specifically, the present invention relates to an electrode for an electrochemical cell, having a solid electrolyte interface layer (passivated layer) which is associated with an active material layer, prior to application of the initial electrical charge. The present invention also relates to a process for producing the electrode and an electrochemical cell having the said electrode.
Lithium based electrochemical cells, such as lithium ion secondary batteries, have been known in the art for several years. Furthermore, passivated electrodes or electrodes having a solid electrolyte interface (SEI) for use in lithium based batteries have recently explored. In accordance with conventional technology, passivation of the electrode occurs during the initial charge/discharge cycle by sacrificing a portion of the cell""s capacity to form the SEI, which, in turn, results in a battery having lowered capacity and coulombic efficiency.
As a result of the present inventors"" earnest studies to solve the above problem, it has been found that the above problem can be solved by using an electrode for an electrochemical cell, previously having a solid electrolyte interface layer.
The present invention has been attained on the basis of the above finding.
The first object of the present invention is to provide an electrode for an electrochemical cell which is capable of preventing from reducing capacity and coulombic efficiency which occurs during the initial charge/discharge cycle by forming the SEI.
The second object of the present invention is to provide an electrochemical cell comprising the said electrode.
The third object of the present invention is to provide a process for producing the said electrode.
The fourth object of the present invention is to provide a process for producing an electrochemical cell having the said electrode.
To attain the above aim, in the first aspect of the present invention, there is provided an electrode for an electrochemical cell comprising:
a current collecting substrate;
an active material layer associated with the substrate; and
solid electrolyte interface layer associated with the active material layer,
the solid electrolyte interface layer containing a reaction product of an aromatic compound.
In the first aspect, it is preferred that the current collecting substrate comprises a metallic mesh. Further, it is preferred that the active material layer include at least one kind of carbonaceous particle.
In the second aspect of the present invention, there is provided an electrochemical cell comprising a first electrode, a second electrode and an electrolyte associated with said first and second electrodes,
at least one of said first electrode and second electrode comprising a current collecting substrate and an active material layer associated with said current collecting substrate,
a solid electrolyte interface being formed on at least one part of surface of the active material by reacting the surface thereof with an aromatic compound.
In the second aspect, it is preferred that the current collecting substrate of at least one of said first electrode and second electrode comprises a metallic mesh. Further, it is preferred that the active material layer of at least one of said first electrode and second electrode include at least one kind of carbonaceous particle.
In the third aspect of the present invention, there is provided a process for producing a pre-passivated electrode for an electrochemical cell, comprising the steps of:
forming a solid electrolyte interface onto at least one part of surface of an active material by contacting the surface thereof with an aromatic compound, and
forming an active material layer comprising the active material having the solid electrolyte interface on a current collecting substrate.
In the third aspect, it is preferred that the aromatic compound comprises a metal salt of aromatic compound.
In the fourth aspect of the present invention, there is provided a process for producing an electrochemical cell having a first electrode, a second electrode and an electrolyte, which process comprises:
forming a solid electrolyte interface onto at least one part of surface of an active material by contacting the surface thereof with an aromatic compound, and
forming an active material layer comprising the active material having the solid electrolyte interface on at least one part of surface thereof, on a current collecting substrate to form at least one first electrode and second electrode, and
associating said electrodes with said electrolyte.
In the fourth aspect, it is preferred that the process further comprises a step of forming a coat on the surface of the active material by an initial charge.
In the fourth aspect, it is preferred that the electrolyte contains as additive.